Expiration of medications, when does their effectiveness decrease?

The expiration of medications is the date until which the stability of the drug in its original container or container is guaranteed, not open or handled and kept in proper condition.

Legally, a maximum expiration limit of 5 years is established. However, it could be less than 5 years and, in that case, it will be indicated on the package.

What is the expiration date of medications?

The real meaning of the expiration date is that corresponds exactly to the period in which the manufacturer insures, and demonstrates with rigorous scientific studies, that the product will retain 100% of the active substance.

The expiration of medications can be expressed according to the 00/0000 format, that is, two figures indicating the month and four figures indicating the year, separated by a slash.

The actual expiration date is the last day of the indicated month. Therefore, the expiration date refers to the expiration of a guarantee of stability and effectiveness. When the expiration date of the medicines is reached, their properties may be affected.

What does the stability of a medicine depend on?

The stability of a medicamentor depends on several factors, Among which are the following:


One of the factors that most affects the preservation of a medicine It is the temperature. That is why it is always advised to keep them in cool and dry places. In addition, make sure that they do not suffer sudden changes in temperature.

Pharmaceutical form and expiry of medicines

If the pharmaceutical form is liquid, such as solutions, suspensions or syrups, they are not as stable as solid forms. In the case of solid pharmaceutical forms, you should check if there is any change in color or physical appearance, although these changes are usually a sign of the degradation of the excipient and not of the active substance.

Multidose medications are those that open several times for administration, Like a syrup or eye drops This can alter the stability of the medication and pose potential risks as to the effect and safety of the medication.

So, once opened, the period of validity is no longer determined by the expiration date, but is described in the leaflet and is usually shorter.

To remember when it was opened, It is advisable to write on the package the date on which it was opened or reconstituted. In any case, it is best to discard the remaining medication after the end of the treatment.

If it is eye drops and the validity time once opened does not appear on the package or leaflet, It is recommended that it be a maximum of 4 weeks.

Discover: What is a eye drops?

Could it continue to be effective a few months later?

According to experts, after the expiration date indicated by the laboratory, the medications may be effective. However, when you respect the expiration date, you are certain that the medicine has not lost activity and there are no potentially toxic substances in it.

Generally speaking, it is possible that nothing will happen to take an expired medication two months ago. However, one thing is that the expired medication remains more or less effective, and another that can become toxic.

What does the science of drug expiration say?

This topic has been researched in recent years in different countries to check the purity and potency of the medications once the expiration date has been reached. However, it must be said that the drugs under study have remained stored in optimal conditions.

The results have been surprising, since a high percentage retained at least 90% of its active substance after the expiration date, a figure considered acceptable for the standards of minimum effectiveness or power expected by the researchers.

Read also: 6 blunders for which medications do not work

How to keep medications

For a drug to remain in optimal safety and efficacy conditions until the expiration date it must be preserved correctly. To achieve this, follow these guidelines:

  • Store it in a cool place., dry and without thermal oscillations.
  • Do not put them near appliances. This way you will avoid electromagnetic fields.
  • Keep them in their original packaging..
  • If you use pillbox, let it be for a few days.


Although most studies state that consuming a drug that has expired a few months ago does not carry a real danger to our health, The most advisable thing is not to take it expired to avoid possible adverse effects.